In tire manufacturing it is necessary or desirable to apply a lubricant to the interior of the tire in order to prepare it for a subsequent heat forming and molding process. At the same time that the lubricant is applied to the interior of the tire, it is convenient to apply paint to the exterior of the tire.
A typical apparatus and method for performing this lubricating and spraying function operates using a linear motion to move the tires to and from various work stations. In such conventional apparatuses and methods, there are typically included a load station, a spray station and a discharge station. The tire is grasped or picked up at the load station by fingers that usually grasp the interior rim of a tire. The fingers are grouped in a finger set and the finger set is typically slideably mounted and carried on an overhead track. The finger set is moved linearly along the track by a chain or belt connected to the fingers. Typically, the chain or belt is an endless loop carried on two spaced sprockets or pulleys, and the finger set is connected to one side of the loop. The tire is moved by the finger set from the load station to the spray station, and at the spray station, the tire is spun while the interior of the tire is sprayed with a lubricant and the exterior of the tire is sprayed with a paint. After the spraying process is completed, the tire and finger set moves toward the load position until the tire is above a discharge station, usually a conveyor belt, where the tire is released and is transported away from the apparatus by the conveyor belt or other discharge apparatus. Finally, the finger set returns to the load position to pick up another tire and the process begins again.
The linear, back and forth, motion of conventional tire handling and spraying apparatuses and methods have been found to be inefficient and illsuited for the operation to be performed by this type of machine. In such conventional machines, the tiregrasping finger set is driven by a chain or belt that is in turn driven by a motor. The chain, and the finger set and the tire must be driven by the motor first in one direction, then stopped, then driven in the opposite direction. The process of stopping and reversing the direction of the chain, the finger set and the tire is an abrupt and rough motion that places undue stress and strain on the equipment. It is difficult and expensive to manufacture a linear motion machine that will smoothly and rapidly accelerate and decelerate using the conventional drive mechanism and, thus, the mechanism is susceptible to rapid wear problems.
Another problem with the linear, back and forth, motion of conventional machines is that the various work stations and the operators running the machine must remain idle for significant periods of time while the tire is at another work station. While the tire and the finger set are in the spray station, the load station and the discharge station are idle. Assuming that there are personnel at the load station and the discharge station to feed tires into the machine and to remove tires from the machine, such personnel will also be idle when the tire and finger set are in the spray position. When the finger set and tire are in the load station, the discharge station and the spray station are idle. And, when the finger set and tire are in the discharge station, the load station and the spray station are idle. The long idle times at each station results in low productivity for both the machine and the personnel operating it.
Also, in the conventional tire handling and spraying apparatuses and methods using a linear motion, it is necessary that one of the work stations be located between the other two work stations. Thus, at some point during the process of moving a tire through the machine, the tire must pass through a work station without performing an operation on the tire at such work station. For example, in one such conventional machine, the discharge station is located between the spray station and the load station. Thus, after the tire is loaded at the load station, it must pass over and through the discharge station on its way to the spray station. The necessity of passing through the discharge station requires that the discharge station be idle at such time and it increases the travel distance and time of the tire and finger set as it moves from the load station to the spray station.
Thus, a need has arisen for an apparatus and method for handling and spraying a tire that reduces the idle time at the work stations relative to known conventional machines, that provides a smooth work motion that is less strenuous and less abrupt than the linear, back and forth, motion of known conventional machines, and that otherwise solves the problems inherent in conventional tire handling and spraying apparatuses and methods.